Device for graphitization of the neck in cathode-ray tube cones

ABSTRACT

A device for the internal graphitization of the surface of the neck in the cone of cathode ray tubes. 
     A device of this type comprises a frame bearing two arms, such as, capable of rotating around an axis, such as, each bearing a collar, for example, each adapted to a given type of cone. This collar has two functions: that of providing for centering along an axis (xx) of the neck of the cone and that of defining a reference line (L r ). 
     With these arms there cooperate, firstly, a supporting table on which the cone is laid and centered in a horizontal plane and, secondly, a graphitization system such that the brush in its top position reaches a determine upper limit (Lg) and, finally, a combination of means providing for the upward translational motion of the supporting table and of the graphitization system, the regulated descent of the latter, the supporting table remaining still during this stage of descent of the brush.

The invention concerns a device that enables the internal graphitizationof the surface of the neck in the cone of cathode-ray tubes.

This graphitization operation is aimed at making this internal surfaceof the neck of the tube conductive to carry it to the same potential (25Kv) as that of the grid which is in contact with the element commonlycalled a "top shield cup".

This operation is delicate because, for reasons of operation of thetube, the maximum height of the graphitization in the neck is a vitalparameter. Furthermore, the thickness of the graphite layer depositedshould be uniform.

For these reasons, the graphitization operations done by hand are notreliable and are increasingly performed by means of automatic machines.Apart from their ability to adjust the height of the graphitizationinside the neck, these machines have to be adapted to the cathode-raytubes according their deflection angle, namely 90° or 110°.

The present invention has precisely the object of resolving all of theseproblems, and concerns a device for the graphitization of the neck of acathode-ray tube cone fitted out with means that make it capable ofreceiving all types of tubes, irrespectively of their deflection angle,said means working together with the graphitization means proper in sucha way that said graphitization is done on a well-determined height ofthe internal surface of the neck, and is done homogeneously.

It concerns, more precisely, a device for the graphitization of the neckin cathode-ray tube cones on a height determined by a plane (Lg);characterized in that it comprises, mounted rotationally on one and thesame frame (110), two arms each fitted out with a collar, the profile ofwhich can be adapted to the deflection angles of the cathode-ray tubes,said collars working together with a supporting table capable of beingtranslated in a vertical plane and provided with means for centering thebase of the cone in a horizontal plane to, on the one hand, center theneck of the cone along its axis (xx) and, on the other hand, determine aplane acting as a reference plane (Lr) for the graphitization operation,of the neck over a determined length (1) equal to the distance betweenthe planes (Lg) and (Lr).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by means of the followingexplanations and the appended figures, of which:

FIG. 1 is a schematic illustration of a device according to theinvention;

FIG. 2 is a diagram illustrating a part of the device of FIG. 1;

FIG. 3 is a top view of the device along the arrow (F) of FIG. 1;

FIGS. 4a and 4b are sections of collars for centering 110° and 90° conenecks;

FIG. 5 is a drawing illustrating a cathode-ray tube, the cone neck ofwhich been coated with graphite by means of the device according to theinvention.

For greater clarity, the same elements bear the same references in allthe figures.

As shown in the figures which give a schematic view of a deviceaccording to the invention, said device essentially consists of:

a frame (110);

a sub-unit (2) formed by a supporting table (4) on which the cone (1)rests, this supporting table (4) being fitted out with a system of stopsfor centering the cone in a horizontal table, this supporting plane (4)being capable of achieving translational motion in a vertical plane;

first and second arms (7a) and (7b) fitted out respectively with acollar (9a) and (9b) having a supporting face against which the cone (1)abuts during the upward movement of the supporting table (4), saidsupporting face demarcating a reference line plane (Lr);

a graphitization system (77) proper, the motion of which is, firstly,related to the vertical translational motion of the supporting table (4)and, secondly, guided by means of a groove (21) with a configuration ofits profile and a positioning that lead the graphitization brush (24) upto the table (Lg) which is the boundary of the zone of the neck (3) tobe graphitized;

a set of jacks, motors, springs, etc., solidly joined to the frame,making the different elements of the device work together.

The working and description of the device according to the inventionshall be dealt with simultaneously by means of FIGS. 1 and 2.

A frame (110) bears all the elements forming the device and, notably,the supporting table (4) of the cone (1) for which the internal surfaceof theneck (3) has to be graphitized.

This supporting table (4) is fitted out, according to one characteristicofthe invention, with a plurality of stops, for example six stops,called centering stops, the structure and working of which areillustrated by means of FIG. 2.

It is seen that each of these six stops (5₁, 5₂, 5₃, 5₄, 5₅, 5₆) isassociated with an independent support (S₁, S₂, S₃, S₄, S₅, S₆) havingan also independent rotation point (P1, P2, P3, P4, P5, P6) solidlyjoined at one end to the supporting table (4).

The links between these supports are achieved by four push rods (T1, T2,T3, T4) having lengths constant for each rod, but not identical to oneother, associated with the supports (S₁, S₂, S₃, S₄, S₅, S₆) in such away that, under the effect of two base centering jacks (C₁) and (C₂),the six stops (5₁, 5₂, 5₃, 5₄, 5₅, 5₆) grip the base of the cone (1)shown schematically by means of dots and dashes in this FIG. 2.

It must be noted that the base centering jack (C₁) controls the support(S₁) and that the base centering jack (C₂) controls the support (S₆).Each independent jack cooperates respectively with pushrods and pullrods (T1, T2, T3) and with the rod (T4) to act upon the supports by apantograph effect and thus bring all the stops into contact with sixpoints (a, b, c, d, e, f) of the rim of the cone (1) which thus getsalmost perfectly centered, along a vertical axis (xx) which correspondsto the axis of the neck (3) of the cone 1.

In FIG. 1, the graphitization device (77) is shown with the cone (1) (insolid lines) placed on the supporting table (4) and centered (4) by thesix stops (5₁) to (5₆). Only one of these stops is arbitrarily marked(5) without any index on this figure.

The cone 1 is therefore centered in a horizontal plane on the supportingtable (4), itself in a low position. It is possible to see, in FIG. 1,twoother cones, symbolized by dashes, which are in this case, is in atop position because, as shall be explained further below, thesupporting table (4) can change position vertically from a bottomposition to a top position. One of the cones has a deflection angle of90° and the other has a deflection angle of 110° .

According to one characteristic of the invention, the first and secondarms(7a) and (7b), solidly joined to the frame (110), can be seen inFIG. 3, while only one is shown in FIG. 1 under the reference (7a).

Each of the first and second arms (7a) and (7b), rotating on an axis(yy) and (zz), is fitted out with a collar (9a) and (9b) adapted to theexternal configuration of the necks (3), which varies as a function ofthedeflection angle of the cone (1) concerned. Thus, as shown in asectional view in FIGS. 4a and 4b, the profiles of the supporting tablesare machined in such a way that the collar (4a) is adapted to the 110°cone while the collar (4b) is adapted to the 90° cone.

It can also be seen, in FIGS. 4a and 4b, that the angles chosen for themachining of each of the cones of the collars is different and, this issoin order to obtain a generatrix against which the cone (1) comes to astop during the upward movement of the supporting table (4). Thisgeneratrix isthen the reference line or plane (Lr).

Before this step of the upward movement of the supporting table (4), theconcerned arm (7a) or (7b) is oriented by rotation on the axis (yy) or(zz) by means of an arm jack (8a) or (8b) in such a way that the axis(xx)of the collar (9a) or (9b) coincides with the axis (xx) of the neck(3). The supporting table (4) is then translated upwards until the coneis supported on the reference line (Lr) of the concerned collar. Underthese conditions, the neck (3) is automatically, precisely andreproducibly centered and positioned for the proper height. Thistranslation of the supporting table (4) is achieved as described below.

Since the collar (9a) or (9b) is placed on the axis (xx), a force on aprimary jack (V), inserts a jack rod (11) therein which raises areinforcement (230), guided by a column (231), that is solidly joinedbothto a graphitization arm (23), bearing the graphitization system(77), and to the supporting table (4). The upward movement of thesupporting table (4) is assisted by a counterweight (10) placed at theend of a counterweight arm (80) that is terminated, at its other end, bya fork (81) to control the upward movement of the supporting table (4).This counterweight arm (80) pivots on an axis (100), and does so untilthe summit of the cone (1) comes into contact with the reference line(Lr) of the concerned collar (9a) or (9b).

The upward movement of the supporting table (4) is accompanied by themovement of the graphitization system (77) which continues until thereinforcement (230) contacts an upward movement limit stop (44).

This graphitization system (77) is formed by a brush (21) and itssupport that rotates eccentrically with respect to the axis of a firstmotor (22).

The brush/motor set (21-22) is fixed to a lever (24), which is itselfhinged on the graphitization arm (23) along the axis (240).

In the idle position, the brush/motor set (21-22) is in horizontalposition. During the upward movement of the rod (11) of the jack (V),the graphitization arm (23) is raised and causes the rotation, on theaxis (240), of the lever (24) and the brush (21) which is solidly joinedto it.

According to one characteristic of the invention, the level (23) followsthe profile of a groove (25) during this upward movement, thus leadingto the obtaining, at the end of travel, of the operational verticalposition of the brush (21) which also gets positioned along an axisparallel to theaxis (xx) of the neck (3) since the axis of the brush(21) is off-centered with respect to the axis of the first motor. Thecombination between the profile and the sizing of the groove (25), onthe one hand, and the fixed position of the collar (9a) or (9b) and ofthe concerned arm (7a) or (7b) as well as the stop (44), on the otherhand, enables the top of the graphitization plane (Lg) to be determinedprecisely and repetitively.

When the first motor (22) is started, it transmits, to the brush (21), arotational motion which, owing to its off-centering, will coat the neck(3) with graphite collected in a container (33). During the applicationofthe graphite, it is nevertheless necessary to communicate a downwardmotionto the brush so as to ensure the bonding of the graphite at thebottom of the neck (3) with the graphite of the cone (1) (FIG. 5).

This downward motion of the brush (21) is achieved, then, according tothe method described below.

The graphitization arm (23)/lever (24) unit is provided at its base witha post, and (26) in contact with a cam (28) connected to a second motor(27).

In the operating position of the device, the brush (21) is in the topposition, the post (26), fixedly attached to the graphitization arm(23), also is in the top position (it is then shown with dashes) and, inthis situation, the cam (28) of the second motor (27) is adapted so thatit is in its minimum travel as can be seen in FIG. 1.

The result thereof is that the starting of the second motor (27) and,consequently, the rotation of the cam (28) drives the graphitization arm(23) downwards and, therefore, by effect of contact, causes the descentofthe brush (21) which, in continuing to rotate, spreads its graphiteover a height corresponding to the maximum travel of the cam (28). It isimportant to note that, during the descending operation of the brush(21) due to the effect of the cam (28) on the post (26), the cam/postcontact is obtained through the effect of a rod (29) which comprises aspring (30). During this stage of the descent of the brush, thesupporting table (4) retains its position.

One of the major characteristics of this mechanism is that thecombination between the profile of the cam (28), on the one hand, andthe rotation speed of this very same cam (28), on the other hand,enables a large number of possibilities of vertical sweeping, causingslow and fast descending motions that effect, among other factors, thethickness and thedistribution of the graphite layers to be deposited.

When the graphitization operation is over, the operations reverse tothose just described are performed.

Release of the force on the jack (V) withdraws the jack rod (11). Thegraphitization arm (23) and the brush (21) descend, simultaneouslylowering the counterweight arm (80) of the counterweight (10) thusassisting in the lowering the supporting table (4) with its cone (1)with the graphitized neck (3).

The base centering jacks (C₁) and (C₂) will then open and releasethestops (5₁, 5₂, 5₃, 5₄, 5₅, 5₆). The arm jack (8) will cause the releaseof a graphitization arm (7) and, consequently, that of the collar (9).

The treated cone (1) will then be withdrawn either by hand ormechanically,and the loading of another cone can be done.

As FIG. 5 shows, the combination of the means applied in the deiceaccording to the invention makes it possible to obtain a graphitizationzone with a length (1) between the reference table (Lr) and the plane(Lg)corresponding to the maximum height reached by the graphitizationbrush (21).

Furthermore, through the configuration of the cam (28) working togetherwith the post (26), the graphitization zone can be extended beneath thereference table (Lr) in such a way that it overlaps the graphite alreadydeposited inside the cone, prior to its processing by means of thedevice according to the invention. This overlapping zone is marked (A)and is shown in FIG. 5 with crossed hatched lines. An anode button (Ba)is shown for reference.

With this device, there may be associated systems for the automaticloadingand unloading of the cones. The cones also may be fed by hand,with the automated system coming into play only in the device itself andaccording to steps of the above-described method.

This device has a great many advantages. In particular, it can beadapted to two types of cone (with deflection angles of 90° and 110°).It enables certainty with respect to the upper boundary (Lg)of thegraphitization of the neck (3) through a graphitization system (77)using a brush (21) that is automatically positioned at the maximumgraphitization height (Lg). It also can be used to adjust the rotationspeed of the brush (21) and its descending speed during thegraphitizationstage. It is a device fitted out with all the centeringand guidance means needed to obtain a constant thickness of graphite,with a well-demarcated height, in doing so automatically andreproducibly.

The invention can be applied, notably, to the manufacture of cathode-raytubes.

I claim:
 1. A method for applying an internal conductive coating to asurface of a neck of a cathode-ray tube cone along a length extendingfrom a coating plane to a reference plane, the method including thesteps ofpositioning a base of a cathode-ray tube cone on a supportingtable of a coating device, orienting a collar about the neck of saidcone, said collar having a supporting face demarcating a referenceplane, centering said cone in a horizontal plane on said supportingtable so that a vertical axis of said collar coincides with a verticalaxis of said neck, raising said supporting table carrying said cone to aposition at which said cone contacts said supporting face of said collarto establish a reference plane relative to said cone, raising a coatingsystem including an arm having a brush/motor set pivotably attachedthereto by a hinge, said brush/motor set being rotatable from ahorizontal position to a vertical position as said arm is raised, abrush of said brush/motor set being disposed within said neck, parallelto and offset with respect to the axis of said neck, at said coatingplane, energizing said brush/motor set to provide rotational motion tosaid brush to apply a uniform conductive coating to said neck,initiating downward motion of the rotating brush from said coating planeto at least said reference plane while retaining said supporting tablein the raised position, said downward motion being provided by a secondmotor having a cam which contacts a post fixedly attached to said arm,said cam driving said arm downward to a point of maximum travel of saidcam, thereby lowering said brush of said brush/motor set through saidneck of said cone.
 2. A device for applying an internal conductivecoating to a surface of a neck of a cathode-ray tube cone along a lengthextending from a coating plane to a reference plane, said devicecomprising a frame havingat least one arm with a collar which adapts tothe neck of said cone, said collar having a supporting face demarcatingsaid reference plane, a table for supporting a base of said cone, saidtable being provided with means for centering the base of said cone andmeans for vertically moving said table so that said cone contacts saidsupporting face of said collar at said reference plane, and internalcoating means for contacting said surface of said neck at said coatingplane and applying a coating of a suitable conductive material theretofrom said coating plane at least to said reference plane.
 3. A devicefor the graphitization of a neck of a cathode-ray tube cone to a heightdetermined by a graphitization plane; the device comprising, mountedrotationally on a frame, two arms each fitted out, respectively, with acollar, the profile of which can be fitted to the deflection angle ofthe cathode-ray tube, said collar mounted for working together with asupporting table capable of being translated in a vertical plane andprovided with means for centering a base of the cone on the table, forcentering the neck of the cone along its axis, and for determining areference plane for the graphitization operation of the neck over apredetermined length, equal to the distance between the graphitizationand reference planes, and means for coating the neck with graphite. 4.The device according to claim 3, further comprising a cam connected to amotor mounted for working together with a post fixedly attached to thegraphitization arm, the profile of the cam being such that its rotationforces the graphitization arm downwards, hence the brush spreadsgraphite at least to the reference plane, and means for retaining thesupporting table in its upward position during the graphitization ofsaid neck.
 5. The device according to claim 4, wherein the combinationof the profile of the cam and of the rotational speed of the motor whichcontrols it are such as to enable variation of the descending speed ofthe brush during the graphitization of said neck.
 6. The deviceaccording to claim 3, wherein the table is elevatable by means of a jackhaving a jack rod which is attached to a reinforcement guided by acolumn, the reinforcement being attached both to a graphitization armbearing said means for coating and to the supporting table.
 7. Thedevice according to claim 6, wherein a counterweight is positioned atthe end of a counterweight arm pivotable about an axis to assist motionof the supporting table.
 8. The device according to claim 6, whereinsaid means for coating includes a brush and its support rotatableeccentrically with respect to an axis of a motor forming a brush/motorset, the brush/motor set being fixed to a lever hinged on thegraphitization arm along an axis in such a way that in an idle position,the brush/motor set is in a horizontal position.
 9. The device accordingto claim 8, wherein said means for coating includes means for guidingthe lever so that, during the upward motion of the jack rod, thegraphitization arm is lifted, thus causing the rotation on the axis ofthe lever, and the brush is placed in a vertical position parallel tothe axis of the neck of the cone.
 10. The device according to claim 9,wherein when in the top position, the brush is at the level of thegraphitization plane.
 11. The device according to claim 9, wherein thebrush is positionable off center relative a said tube and when the brushis in the top and maximum position the motor can communicate arotational motion to the brush which due to being off center can coatthe neck of the tube with graphite.